title: Survival after shock therapy in implantable cardioverter-defibrillator and cardiac resynchronization therapy-defibrillator recipients according to rhythm shocked. The ALTITUDE survival by rhythm study.
abstract: OBJECTIVE
  This study sought to determine if the risk of mortality associated with inappropriate implantable cardioverter-defibrillator (ICD) shocks is due to the underlying arrhythmia or the shock itself.
  
  
  BACKGROUND
  Shocks delivered from ICDs are associated with an increased risk of mortality. It is unknown if all patients who experience inappropriate ICD shocks have an increased risk of death.
  
  
  METHODS
  We evaluated survival outcomes in patients with an ICD and a cardiac resynchronization therapy defibrillator enrolled in the LATITUDE remote monitoring system (Boston Scientific Corp., Natick, Massachusetts) through January 1, 2010. First shock episode rhythms from 3,809 patients who acutely survived the initial shock were adjudicated by 7 electrophysiologists. Patients with a shock were matched to patients without a shock (n = 3,630) by age at implant, implant year, sex, and device type.
  
  
  RESULTS
  The mean age of the study group was 64 ± 13 years, and 78% were male. Compared with no shock, there was an increased rate of mortality in those who received their first shock for monomorphic ventricular tachycardia (hazard ratio [HR]: 1.65, p < 0.0001), ventricular fibrillation/polymorphic ventricular tachycardia (HR: 2.10, p < 0.0001), and atrial fibrillation/flutter (HR: 1.61, p = 0.003). In contrast, mortality after first shocks due to sinus tachycardia and supraventricular tachycardia (HR: 0.97, p = 0.86) and noise/artifact/oversensing (HR: 0.91, p = 0.76) was comparable to that in patients without a shock.
  
  
  CONCLUSIONS
  Compared with no shock, those who received their first shock for ventricular rhythms and atrial fibrillation had an increased risk of death. There was no significant difference in survival after inappropriate shocks for sinus tachycardia or noise/artifact/oversensing. In this study, the adverse prognosis after first shock appears to be more related to the underlying arrhythmia than to an adverse effect from the shock itself.
authors.affiliation: Division of Cardiovascular Disease, Sanger Heart & Vascular Institute, Charlotte, North Carolina. Electronic address: powell.brian17@gmail.com.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Powell
authors.affiliation: Division of Cardiovascular Disease, University of Southern California, Los Angeles, California.
authors.forename: Leslie A
authors.initials: LA
authors.lastname: Saxon
authors.affiliation: Division of Cardiovascular Disease, Penn State Milton S. Hershey Medical Center, Hershey, Pennsylvania.
authors.forename: John P
authors.initials: JP
authors.lastname: Boehmer
authors.affiliation: Division of Cardiovascular Disease, Intermountain Medical Center, Salt Lake City, Utah.
authors.forename: John D
authors.initials: JD
authors.lastname: Day
authors.affiliation: Division of Cardiovascular Disease, Cardiology Associates of Northeast Arkansas, Jonesboro, Arkansas.
authors.forename: F Roosevelt
authors.initials: FR
authors.lastname: Gilliam
authors.affiliation: Division of Cardiovascular Disease, VA Palo Alto Health Care System, Palo Alto, California.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Heidenreich
authors.affiliation: Biostatistics, Boston Scientific, St. Paul, Minnesota.
authors.forename: Paul W
authors.initials: PW
authors.lastname: Jones
authors.affiliation: Biostatistics, Boston Scientific, St. Paul, Minnesota.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Rousseau
authors.affiliation: Division of Cardiovascular Disease, Mayo Clinic, Rochester, Minnesota.
authors.forename: David L
authors.initials: DL
authors.lastname: Hayes
mesh_terms: D001145:Arrhythmias, Cardiac / Q000401:mortality* / Q000628:therapy*; D016477:Artifacts; D058409:Cardiac Resynchronization Therapy Devices; D017147:Defibrillators, Implantable; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D016555:Matched-Pair Analysis; D008875:Middle Aged; D011446:Prospective Studies; D013686:Telemetry
keywords: AF; AFL; CI; CRT-D; HR; ICD; MVT; PMVT; SVT; VF; VT; atrial fibrillation; atrial flutter; cardiac resynchronization therapy; cardiac resynchronization therapy defibrillator; confidence interval; hazard ratio; implantable cardioverter defibrillators; implantable cardioverter-defibrillator; monomorphic ventricular tachycardia; polymorphic ventricular tachycardia; supraventricular tachycardia; ventricular fibrillation; ventricular tachycardia